1. Field of the Invention
The subject invention relates to voltage regulators and more particularly to voltage regulators for use in pulsed systems such as pulsed radars.
2. Description of Related Art
Pulsed systems such as pulsed radars present a highly dynamic load to power conversion and regulating systems. In order to meet the system stability requirements of proposed radars using solid state RF amplifiers, it is anticipated that the bias voltages to the transistors of such solid state amplifiers will have to be very stable, i.e., well regulated. Analysis has shown that it is very desirable to provide the required regulation at the point of use.
Present systems lack the ability to provide highly stable bias voltages in a cost and power efficient manner. In the prior art, large capacitor banks have been employed to meet the voltage stability requirements of dynamic loads in radar. The size and weight of systems employing such capacitor banks increase directly with increased performance requirements. The type and number of capacitors required in such systems lowers system reliability. Capacitor banks must also be distributed across the antenna when distributed RF power stages are employed on the antenna, which imposes undesirable volume and weight penalties on the antenna.
The prior art has also employed linear regulators in radar power supply systems. Such prior art linear regulators have been low in efficiency and have still required large capacitor banks. The size of the capacitor banks is a trade-off against efficiency. Maintaining response time and stability of prior art systems employing linear regulators also requires complicated drive circuitry for the pass element of the linear regulator.
One measure of a regulation system's stability is the time required for the system to return to its steady state or at-rest condition after the system has been perturbed by external (or internal) causes, i.e., transient response. An example of such a perturbation is the pulsed or dynamic loading presented to a power converter by a pulsed radar. With respect to a linear regulator, stability may be measured by the time it takes for the output voltage of the linear regulator to return to its steady state value after a step change in load current, such as a step from a no load to a full load condition. Where linear regulators employ field effect transistors, the so-called Miller Effect increases the time it takes the linear regulator's output voltage to return to its steady state value after a load current change and hence impairs the stability of the system.